Method of washing dishes or the like



March 2, 1954 E. s. STODDARD 2,671,037

METHODS OF WASHING DISHES OR THE LIKE Fiied Sept. 10, 1949 2Sheets-Sheet 1 IN VEN TOR.

EDGAR S. STODDARD ATTYS.

' Patented Mar. 2, 1954 Maroon QE'WASH N SLH fi on THE BIKE Edgar S.stoddardhlierwynr 111;. assignon-to Gen,-

e cir Q mna a e/ unatic at Ne Yor Application September 10, IiMQ, SerialNo. 114,956

, I The present invention relates to methods dishes, or the like.aconventional dishwashing apparatus, the liquid employed in thevatforb'oth washing" and rinsing purposes is hot water; and the dishesmay be subjected to a primary washing step am ithen a secondary washingstep, followed by a primary rinsing step and then a secondary rinsingstep, the individual steps consuming predetermined time intervalsestablished by a program controller incorporated in the apparatus; Atthe conclusion of each step, the used cl' argeof hot water contained" inthe vat is drained therefrom, and then a fresh charge of hot waterisintrodllccd into the vat to be used in carrying the succeeding stepNormally a charge of detergent is introduced into the charge ofhotwater-contained in the vat at the begirming of; the primarywashingstep; while the secondary washingstep is carried out without theaddition of a new charge of detergent, since a small residuum of theinitial charge of detergent is present in the" vat following drain- ,i ipf the used charge of hot water at theconof: the primary washing step,This residis present in the vat as a result ofa small nortion ofthe usedcharge of hot water adhering to the dishes-andto the rack supporting thedishes and remaining inthe joints the walls gtjt'he vat and inthe drainmechanism connecting'the lower portion of the vat to the associateddrain Qonduit." Both. the" primary rinsing step and th ondary i s n s ecarried (o usin only the charges of fresh hot water in order positivelyto eliminate anyfilms of detergent from; the dishes Ultimately, thedishes n ay be subjected to a blast of hot an order to. effect a dryingaction thereupon.

While, thisimethod of washing dishes is highly satisfactory when softwater is employed, it is not entirely successful when hardwater isemployed due to: the presence therein or the carbonates ofca'lcium andmagnesium Specifically, the dishes, after being dried, are somewhatstreaked or spottedand are thus robbed oftheir natural luster andsparkle. This; spotting is especially noticeable on glassware, andparticularly on- Stemware, the spots having a; white: or,

grayish, outline of irregular configuration.

efieet ma he d tec sin sle th fqrmo a general discoloration of. theglassware. even in those, areas having, only slightly hard water.

ii yhilethe.provisionloiwater oit ningequipm nt whims. (011M725) in theplumbing preceding the dishwashlng ap paratus in: hard water localitiesis helpful in: re; ducing the rate at which this progressiue im pairmentof the luster of. the glassware pros coeds, it doesnot. prevent the;ultimate impair,- ment noted, and the equipment does not. worksatisfactorily without. frequent attention with particularreerencetorecharging In studying this problemit has been, discoveredthat this spotting of the glassware is directly traceable to: the dryingthereon of rather large droplets of rinsing water, containing calciumcarbonate and other hard watercomponents. following the secondary orfinal; rinsing step, and that this spotting may be. prevented byelimimating the-dropletsfrom the glassware. immedi ately following thesecondary or final rinsing step preceding drying, even though hard wateris employed. Further, it hasv been discovered that this objective may beachieved by introducing a suitable synthetic wetting agent into the. hotwater contained in the vat in the secondary or final rinsing step,whereby the surface tension of the water is sufficiently reduced tocause it to run freely from the glassware so that no water droplets ofany appreciable size remain on the glassware at the conclusion of thesecondary or final rinsing step' and preceding drying ofthe glassware.

In carrying out t s method it is preferred that a liquid syntheticwetting agent be employed and that anexcess charge thereof be introducedinto the charge of hot'water' contained in the vat in the-primaryrinsingstep so that the desired effect is also achieved in this step.Then when the secondary or final rinsingstepis carried out, a sufiicientcharge of the wetting agent will-be'pres'ent in the charge .of-hot watercon.-

"tained in the vat, since a residuum of the initial excess charge of thesynthetic wetting agent is present in the vat following draining of the,used chargeof hot water at the conclusionof the primaryrinsing step,this residuum being present in. the vat due to the circumstancespreviously noted- 1 Acccrdingly,it is ageneral object of the -presentinvention to provide an improved method of washing dishes, or the like,that preserv'iestlie natural luster and sparkle thereof and preventsstreaking and spotting thereof incident to dryins- Another object of;the invention is to provide a method of washing dishes, or thel-ikefthat in- ,1 e u es a mp o d rinsing. st e p oY hotwater-'centaining a' synthetic wetting agentl' F r er ailuresarde t ic rm-noes particular arrangement of the steps of the method, whereby theabove-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the following specification taken inconnection with the accompanying drawings, in which Figure 1 is a frontelevational view, partly broken away, of dishwashing apparatus in whichthe method of the present invention may be carried out; Fig. 2 is avertical sectional view of the dishwashing apparatus, taken in thedirection of the arrows along the line 2-2 2, illustrating the frontdoor in its open position and the dish-supporting rack in its withdrawnposition, wherein it is carried by the front door; Fig. 4 is an enlargedside elevational view of the synthetic wetting agent receptacle that iscarried by the dish-supporting rack, as illustrated in Figs. 2 and 3;Fig. 5 is an enlarged plan view of the synthetic wetting agentreceptacle shown in Fig. 4; and Fig. 6 is an enlarged front elevationalview, partly in section, of the synthetic wetting agent receptacle shownin Figs. 4 and 5.

Referring now to Figs. 1 and 2 of the drawings, there is generallyillustrated automatic dishwashing apparatus ID that is preferably of thecharacter of that disclosed in the copending application of Edgar S.Stoddard, Serial No. 105,618, filed July 19, 1949, now Patent Number2,635,941, and incorporating a wetting agent receptacle and embodyingstructure for carrying out the method of the present invention. Thedishwashing apparatus I is of the gasketlessdoor front-opening typeincluding a cabinet I! housing a substantially vertically disposed ,vat|2, the cabinet I! and the vat |2 having substantially aligned frontopenings that are closed by a front door H3. The front door I3 ispivotally mounted adjacent to the lower edge thereof within the lowerportion of the vat l2 and is movable between a substantially verticalclosed position and .a substantially horizontal open position. .Also,the dishwashing apparatus H comprises movable rack structure |4 that isadapted to support dishes, and other utensils, within the vat l2 forwashing purposes, the rack structure I4 being movable into and out ofthe vat l2 through the front openings when the door l3 occupies its openposition. An impeller I5 is arranged within a sump l6 formed in thelower portion of the vat I2 and is rotated by an associated electricoperating motor H for the purpose of producing a washing action withinthe vat |2 when the door l3 occupies its closed position and washingliquid is contained in the sump 16. More particularly, the impeller I5is rotated in the counterclockwise direction as viewed from the top ofthe vat l2 in order to produce an upward swirl of the washing liquid orthe rinsing liquid through the rack structure l4 supporting the dishesand other utensils, whereby the washing liquid or the rinsing-liquid isthrown upwardly into bombarding relation with the dishes supported bythe rack structure I4 and then falls downwardly back into the sump Hi tobe recirculated.

For the purpose of supplying washing liquid or rinsing'liquid to the vatl2, there is provided an inlet conduit connected to a suitable source ofwashing liquid or rinsing liquid, such, for example, as a hot watertank. The inlet conduit 28 communicates with the inlet port of an inletvalve 2| of the solenoid controlled type; and the outlet port of theinlet valve 2| communicates with a conduit 22 that is connected to aspraying device 23 arranged in a depression 25 formed substantiallycentrally within the top wall of the vat I2. The inlet valve 2| is ofthe fast-opening, slow-closing type, being governed by an associatedclashpot so as to prevent water hammer in the plumbing communicatingwith the inlet conduit 2G. The inlet valve 2| is normally biased intoits closed position, and when the solenoid 2 thereof is energized, it isoperated into its open position in order that the hot water may besupplied from the inlet conduit 28 to the spraying device 23, wherebythe hot water is sprayed downwardly in a rotating swirl by the sprayingdevice 23 from the top of the vat l2 through the rack structure l4 andaccumulates in the sump I6. Subsequently, when the solenoid 2| of theinlet valve 2| is de-energized, the inlet valve 2| is moved slowly fromits open position into its closed position in order to cut off thesupply of hot water from the inlet conduit 20 to the spraying device 23.

For the purpose of controlling the retention of washing liquid orrinsing liquid in the sump [6, there is provided a drain mechanism 30 ofthe solenoid controlled type. The drain mechanism 30 comprises aflexible conduit 3|, one end of which communicates with a drain fixture32 provided in the lower portion of the sump I6, and the other end ofwhich communicates with a drain conduit 33 that is connected via a trap,or the like, not shown, to drain plumbing, not shown. The flexibleconduit 3| is normally biased by its weight into its lower portion inorder to place the interior of the sump I6 into free drainingcommunication with the drain conduit 33 so that any washing liquid orrinsing liquid accumulating in the sump It runs through the flexibleconduit 3| into the drain conduit 33; and when the solenoid 3e thereofis energized the flexible conduit 3| is elevated into its upper portionin order to cut off the free draining communication between the interiorof the sump may be retained in the sump l5.

ing liquid or rinsing liquid from the sump i6.

For the purpose of effecting drying of the dishes and other utensilssupported by the rack structure I4 within the vat l2, there is provideda heating unit or element 40 that is preferably of the sheathedresistance conductor type. The heating element 40 is disposed in thelower portion of the vat I2 :below the rack structure 14 and insurrounding relation with respect to the impeller l5 so that air blownby the blades of the rotating impeller l5 contacts the heating element40 and then moves upwardly through the rackstructure l4 into contactwith the dishes and other utensils supported by the rack structure M inthe vat l2. The lower portion of the door l3 carries a detergent cup 4|opening toward the interior of the vat |2 that is adapted to receive acharge of detergent. Preferably the detergent that is employed in thedetergent cup 6| is of the type sold under the trade name Calgonite thatcomprises about 40 per cent sodium hexametaphosphate and 60 per centsodium meta-silicate 1 As best shown in Fig. 3 therack structure I4 isremovable as a whole fromthe door l3 in its been Peesitie'n theeoinpri'ses va vrower dishreek t2 tied a detachable upper dishrack as.The upper dishreclg #3, in turn, comprises an outer marginal section 44ehd an inner detachable central section 4'5 hlso the central portion ofthe lower dishr'ack 42 carries a perforated silverware oas- Ret l6.Normally, the plates and other large dishes; are ermngea in the'lowerflishrackli'; and the siliz'erwar'e 'alrrimjged in the basket 46.Also, the taps and saucers are normally 'arraJnged -i-n the outermarginal section '4} of the upper .dish en; {33; While the drinkingglasses tumblers, and thelike, are normally arreneefi inthecentrallisecnan E5 of the Kipper dishrack 13. Finally, the centralportion of the central sectionlii of the up- ,per dishrack 13 comprisesan upwardly eitend ing ptstenjtiauy cylindrical open-work element 4.1disfob'sed substantially directly below the sprayin device when theraekstruetu e M occupies Tits fnofrhel p'ositionjin the 'vet 12 whichVeentrell .0551- iinderfelerh'ent l! carries .a wetting agentrece'iit'a'cleT'll. Thus'w henlthe rack structure I4 ciifiie's itsnormal. position in the 'vat T2 the wetra "adjacent to the sprayingdevice .23 for a In' irpos'e mere ruuy gexpl ineu hereih'aiter.

best "s een in Figs. lto 'fi fin'clusive,the Syn- Ttli'tic 'iiitftih'ga'giit recepteeie 50 comprises a isulis'th htiall-y 'dylfiidfidell "may'51 provided with a eiitiell'y icirciilel'r liiiiged top cover 52, the 2theupper'mrtronicf cover 52, the valve .elernent fi'belngmountefl ferFihellyfthe ree'epteae 5lfeom prises msiibstantmHy-m sneped "tubeorsiphon f'device l gm-ojbiit'ih'g through'zthe upperportidn ofthe-cylindrieel side wel1r5l ,-'-the siphon element sfi l including legM disposed within the :cylindrical ibodyaSl endear-ejectingdownwardlyand-terminating rad- :isee'enmo 'the bottom wall' @thereof andemlegii=63 Hisensed:exteribrlyiof thecylindrical bodyt lend firojecting 5downwardly below ithe whet-tom wall thereof. As'v the hot'waiterfissaccumulated inane receptacle '50 the head of liquid thereinrises unt iiigtegerit'iecptacle'iifl is disposed directly bilow til itreaches a level indicated generality at.

whereby a predetermined quantity of liquid has been accumulated in thereceptacle 50. The'liguid then flows between the legs '62 and $3 of 5the siphon device 61 falling through the leg 68 and producing a siphonaction between the legs 53 and 62 in a. well-known manner, wherebysubstantiallyth'e "entire liqnid contents-of the -reee ptable '50 isdischarged by the siphon device 6 into-the vat 12. Thus it will beunderstood that when a. predetermined quantity ef liquid is eclcumulatedwithin the receptacle 50 that substratetia'lly the entire liquidcontents thereof is eutematicall y discharged therefrom' bythe sip'h0n;levice ti"! into :the Wet "1-2 which arrangement is utilized for apurpose more-fully explained here- *ina'fter.

The synthetic wetting agent that may =be employed in the receptacle 50may be of any suit- Mile txpe although it preferable that fit he {in'thetorm of a liquid, and-it i-has -'bee n found *that fa fgreaitvariety "of 'the sulfuric acid esters of the Iiigherfla'tty acids areadmirably suitedtc this end. For examples, sodium lauryl sulfateendoctzdecyl sodium sulfate are quite satisfactory. filso, the long cheiinsul'fonates rare suitable and 's'o'dium' lauryl *s iltonate "andoeta'deeyl sodium sul-fcnate have -'been found *toibe satisfactory."chemical compositions of *these synthetic wetting agents "form no part-01 -the present in- 'viention end-any isyntheticwetting egent-"iseuit--e'ble thatipossesses'the cheracteristic oi redueing the" surface"tension of hot water sufificientl yto cause -the *hot water montactingthe*dishes and r lessware to run*rreely end quickly therefrom ;in--jorder-*to"prevent the'presenceofiairlyflargexiiplets of rinse water*on the dishes and -glesswe-re following the secondary-or fina-M'insi-ngstep, and preceding drying, as explained more ,ful-lfihere inetter.

'Fen the purpose deflecting-coordinated, opera,- tion of -thevmious-"ccntrol" elements incorporgated d-ishwashing'trpparatns I D"inorder to aceemplish-a-'-complete 'eyele -of operationfithereilsincorporatedwherein-an electric -c,on;trol circuit andprog ra rncontroller rof it-he-eharacter'of that eis'close'd inthecoperrdingapplication of Doug-les Iii-ismiaseriamos-egeoe; filedMey 7;=1-'94,9,.erms circu'it *eentro1 arrangement itnclu'desz a mfogram eoritroller efthe timerrtypedndicatedgenerally ttt-ti end-*fiisposed="irrithempperleft hendjfiront insertion of thefelpperetus itbetween theadj ecentharid side' wall of the cabinet H en'd the hBJnd-Sifi8"W ai11-Df'ithe'Vat 12,4. eneasuringeoil'or relay 12 disposed in the-flower efileft-herld from-r pertierr of theTaDPara'tus {B hettteenthe-adjacent--'1eft herrd' sideiwa'll of jt-he cebinet' l I and the a djeeerfi't left-hand side 'wall the' b ottom weill of thewat w andcontrolled-*hy "fiihe movements' 'of' the -front door ts. err-h 1 bgramcontrcllerfll comprises an-felectric drive mttorfinot shown, "of-'the'-"timer: typeysirch tor -fexam"pl e,v as :a "Telechron motor,switching structure; not howni an an 'operetineislieftrtheiiefxtendslthroujehtheifrontwell of "thewhinetggl a flla-iidxsupnorts anotataihle eontro'l. knob'1;1j4.. .,that see-operates iwithhnelindiciainlets 1.5 ithat isedi- ,trectl mountedeediecentstheretc unonuthe Kent':.'splratee3:5;:; .the windieie @notednbein v I wheeler spac deeprterelatien- :sD .ieoursemt. circuit control arrangement also includesthe electric operating motor ll, the operating solenoid 2| of the inletvalve 2!, the operating solenoid 38' of the drain mechanism 38, and theelectric heating element 40; and finally the circuit control arrangementincludes a source of current supply that may be of 115 volts 60 cycle A.C.-

The details of the connection and arrangement of the circuit network inorder to accomplish a complete washing cycle in the dishwashingapparatus is form no part of the present invention, and in the interestof brevity only the overall cycle of operation of the apparatus ID willbe described with particularity.

In order to prepare the dishwashing apparatus ID for a cycle ofoperation, the dishes, glassware and other utensils are appropriatelyloaded into the rack structure hi; and a. predetermined charge of theliquid synthetic wetting agent mentioned is placed within the body 5! ofthe receptacle 50 through the open top thereof while the cover 52occupies its open position. The cover 52 is then returned to its closedposition with respect to the open top of the body 5|; and it may beassumed that the valve element 55 cccupies an adjusted position withrespect to the cover 52 so that the liquid contents of the wetting agentreceptacle 50 will be discharged'by the siphon device 6i during theprimary rinsing step, as explained more fully hereinafter. The rackstructure It is then pushed forwardly into the vat I2 into its normalposition, whereby the cover 52 of the wetting agent receptacle 50 isdisposed immediately below the rotary spraying device 23. A charge ofthe detergent noted is then placed in the detergent cup 4! provided inthe lower inner wall of the door [3; and the door 13 is moved from itsopen position into its closed position.

The rotatable control knob '14 is then rotated from its Off positioninto its On position initiating operation of the program selector H andthe electric control network. Specifically, at this time the programselector Tl initiates operation of the operating motor I! and initiatesoperation of the timer motor incorporated in the program selector 7!.The operating motor I! rotates the impeller i5 in the counterclockwisedirection as viewed from the top of the vat l2; and the timer motordrives the control knob 14 continuously in the clockwise direction. asviewed in Fig. 1, at a predetermined rate and ultimately back into itsOil? position. After an elapsed time interval of approximately 90seconds, the program controller H efiects energization of the inletvalve solenoid 2i, whereby the inlet valve 2| is operated from itsclosed position into its open position so that washing liquid may hesupplied from the supply conduit 20 to the spraying device 23. Thewashing liquid is sprayed downwardly from the spraying device 23 intothe vat i2 and through the dishes supported by the rack structure It andaccumulates in the sump 16 from which it is drained through the drainmechanism 30 directly into the drain conduit 33 since the drainmechanism 30 occupies...

ing device 23 enters the wetting agent receptacle 5!) and is accumulatedtherein, along with the liquid wetting agent already in the receptacle50. Approximately 30 seconds after the inlet valve 2! is thus operatedinto its open position, the program controller 'i'l energizes thesolenoid 30' of the drain mechanism 3i whereby the drain mechanism 30 isoperated from its draining position into its non-draining position sothat the washing liquid is accumulated in the sump I6. At this time thewashing liquid accumulating in the sump I6 is caught by the blades ofthe impeller l5 and is flung upwardly through the rack structure it andthe dishes supported thereby against the walls of the vat i2 and thedoor l3 and again returns to the sump l6.

The supply of washin liquid from the spraying device 23 continues and asthe quantity of washing liquid accumulating in the sump 16 increases,the load imposed upon the impeller I5 is gradually increased, thecurrent drawn by the motor ll being gradually increased and metered bythe measuring coil or relay 72. When a predetermined quantity of washingliquid accumulates in the sump 15 a correspcnding predetermined load isimposed upon the operating motor ll, whereby the current metered by themeasuring relay 12 reaches a predetermined value. When this currenttraversin the relay I2 reaches the predetermined value mentioned,indicating that the vat i2 now contains a full and predeterminedquantity of washing liquid, the measuring relay 12 operates and effectsde-energization of the solenoid 2i i the inlet valve 2|, whereby theinlet valve ii is slowly returned from its open position into its closedposition. Shortly thereafter the inlet valve 21 is completely closedcutting off the supply of washing liquid from the supply conduit 28 tothe spraying device 23.

Approximately 45 seconds after the drain mechanism 39 is operated intoits non-draining position, the program controller ll further opens thecircuit for energizing the solenoid 2! of the inlet valve 2 I, therebyproviding a timed arrangement for effecting the return of the inletvalve 2i into its closed position in the event this result has notalready been brough about by operation of the measuring relay '52 withinthe &5 seconds period mentioned.

The primary washing step is thus initiated upon the operation of thedrain mechanism so into its non-draining position, and continues for atotal time interval ofapproximately 330 seconds; and within this timeinterval and in response to the accumulation of a predetermined quantityof washing liquid in the sump it, the charge of detergent contained inthe detergent cup 5| is introduced into the washing liquid contained inthe vat 52 in order that the primary washing step may be effective toremove grease and other foreign materials from the dishes supported bythe rack structure Hi. The arrangement for introducing the detergent isdisclosed in the copending application of Forrest A. Walker, Serial No.57,448, filed October 30, 1948, and is based upon the accumulation of apredetermined quantity of washing liquid in the sump it during theprimary washing step, whereby the washing liquid accumulating in thesump it is flushed or washed into the detergent cup ii carried by theinner wall of the door 13 causing the detergent contained therein to bewashed into the body of washing liquid contained in the vat l2. Thisintroduction of the detergent into the washing liquid conanew ,9 tainedin- .the vat-4.2 is accomplishedshortly. .101! lowing theloperation ofthe drainv mechanism 311 into its non-draining ,position'initiating. thebeginning of the primary washing step sothat the detergent is present inthe washingl-iquid during alsubstantial part of the time intervalof thepri-. mary washing step.

Atthe conclusion of the pr nary washing step the program controller 1|opens the circuit for. energizing the solenoid 3d of the drain mechanism38, whereby the drain mechanism 39 is returnedfrom its non-drainingposition into its draining position so that the washing liquidand thecarried detergent contained in the sump .l fi is drained therefrom in avery short interval of time; and approximately 45 seconds after thedrain mechanism 38 is operated into-its drainin position, the programcontroller 11 again closes the circuit for en'rg-izing. the solenoid 21of; the inlet valve 2!, whereby washing liquid is again supplied to thespraying device 23 and is again sprayed downwardly into the vat 1-2.Approximately seconds after the inlet'valve 2i isoperated into its openpositionthe program controller 1-! recloses the circuit for energizingthe solenoid 33' of the drain mechanism 30, whereby the drain mechanism30 is operated into its non-draining position in order to initiate 'asecondary washingstep.

The secondary washing step proceeds in the manner ofv the primarywashing step described above; however, without the addition of ,anothercharge of detergent since a residual amount of the initial charge ofdetergent remains in the vat l2 from the primary washing step. Thisresiduum of the detergent-is presentxintheivat 12 since a small portionof the charge or washing liquid contained in 'the'vat i2 during theprimary-wa'shing step remain therein due to" adherence to the dishesand'the rack structure 14 and dueto its presence on the wall structureof the vat l2 and inthe drain mechanism 30. Specificallmthe inlet valve2 is subsequently operated into-its closed position undenthe control ofthe measuring relay 12 dependent upon theload upon the operating motor17, or under the control of the program controller H; all in themannerpreviously explained. In-any case, after a time inter; valorapproximately 45 seconds following opera tion of the drain mechanismcflinto its nondraining positionthe inlet valve 2| is operated into itsclosed position. At this time the inlet valve 2i occupies its closedposition and the drain mechanism 3! occupies its non-draining position,whereby the secondary washing step continues in the manner previouslyexplained. As the washing'liquidissprayed downwardly from the spray-'-ing device 23' into the vat .l 2 during. 'thesecondary washing step.additional liquid is accumulated in the wetting agent receptacle 58. fThe secondary washing step continues for a time'i-nterval ofapproximately 330 seconds following operation of the drain mechanisminto its -non-draining position; whereupon the program selector llefiects the return of the drain mechanism 3!; into its. drainingposition as previously explained.

'The washing liquid accumulated in the sump it is drained into the drainconduit 33 in the manner previously explained in a very short timeinterval; and approximately 45 seconds after-the drain mechanism 3B isoperated into its drain ing position the program selector fllagain0perates the .inlet' valvelzl' into its open position. The rinsingliquid is then sprayed downwardly It) into .thevat. 1.2.. by thespraying device. 23 for a time interval ofapproximately 10,.Seconds;whereupon the program controller TI again returns .thedrain mechanism 30into its non-draining position, initiating a primary rinsing step.

Theprimary rinsing step proceeds in a mannerv substantially identical tothe primary washing step described above, whereby the inlet valve 2 issubsequently operated into its closed position under the control of themeasuring relay l2 dependent upon the load upon the operating motorv H,or under the control of the program selector .H; all in the mannerpreviously explained. In any case. after a time interval ofapproximately 45 seconds following operation of the drain mechanism '30into its non-draining position, the inlet valve .21 is operated into itsclosed position. The primary rinsing step continues for a time intervalof approximately .90 seconds following the operation of the drainmechanism 36 into its non-draining position, whereupon the programselector H effects the return of the drain mechanism 30 into itsdraining position.

As the rinsing liquid is sprayed downwardly from the spraying-device 23into the vat i2 during the primary rinsing step, additional liquid isaccumulated in the wetting agent receptacle 58, whereby a predeterminedtotal head of liquid is accumulated in the receptacle 50 causing thesiphon device 6! to operate automatically to discharge substantially theentire liquid contents of the receptacle 5.3 into the vat i2. The chargeof wetting agentthus introduced into the charge of ..rinsing liquidcontained in the vat 12 reduces the surface tension thereof so that therinsing liquid runs freely from the dishessupported by the rackstructure l4.

The rinsing. liquid accumulated in the sump .ifi'is drained into thedrain conduit 33 at the conclusionv of the primary rinsing step in themanner previously explained in a short time interval; and approximately45 seconds after the drain mechanism 30 is operated into its drainingposition, the program selector H reoperates the inlet valve 2| into itsopenposition. The rinsing liquid is sprayed downwardly from the.spraying device 23 into the vat l2; and approximately 10 secondsfollowing operation .of theinlet valve'2i into its open position theprogram selector. H effects operation of. the drain mechanism 30ln'toits non-draining position in order to initiate a secondary rinse step.

The secondary rinsing step proceeds in-a manner substantially identicalto the primary rinsing step described. above except that no additionalcharge of synthetic wetting agent is in trocluced into the charge. ofrinsing liquid con.- tained in the vat .12. .The inlet valve '21 issubsequently operated into its .closed'position under the control of themeasuring relay 1.2 dependent upon the load uponthe operating motor IT,or under the control of the program selector l I; all in the mannerpreviously explained. In any case, after a time interval ofapproximately 45 seconds following operation of the drain. mechanism sointo its non-draining position, the inlet valve .2! is operated intoitsclosed position. The secondary rinsing step continues for a timeinterval oiapproximately seconds following the operating of the drainingmechanism 3B into its nonedrainingj position, whereupon thelprogramselector H eifects the return of the drain 'meche anis'ni so into. itsdraining .positionj i "T h e rinsingliciuid -.accumulated in the sump Vwhen - ll. I is drained into the drain conduit 33 in the mannerpreviously explained in a short time interval; and approximately 45seconds after the drain mechanism 30 is operated into its drainingposition, the program selector H closes the circuit for energizing theheating element 40, whereby heat produced by the heating element 48 iscirculated in the vat I2 by the blades of the impeller It: in the formof an upwardly directed blast of hot air into contact with the dishessupported by the rack structure I 4.

Since a residuum of the synthetic wetting agent is present in the bodyof rinsing liquid contained in the vat I2 during the secondary rinsingstep, due to the circumstances previously noted, the surface tension ofthe rinsing liquid is sufficiently reduced so that it readily runs offthe dishes supported by the rack structure I4 at the conclusion of thesecondary rinsing step. Accordingly, at this time when the drying stepis initiated there are no droplets of rinsing liquid of any considerablesize adhering to the dishes supported by the rack structure M. The hotair circulated in the vat I2 by the impeller is directed into contactwith the dishes supported by the rack struc ture I4 effecting a dryingaction thereupon, and is thence circulated back into contact with theheating element 40 by the impeller I5.

This action constitutes an initial drying step and is continued for atime interval of approximately 1200 seconds, whereupon the programselector II opens the circuit for energizing the operating motor I!while retaining closed the circuit for energizing the heating element46. Accordingly, the operating motor I! stops, arresting the rotation ofthe impeller I5, while the generation of heat by the heating element 40continues. Thus drying of the dishes supported by the rack structure I 4continues through a final drying step after operation of the impeller I5 has been arrested. The final drying step continues for a time intervalof approximately 600 seconds, whereupon the program controller IIinterrupts the circuit for energizin the heating element 46, as swell asthe circuit for operating the timer motor incorporated in the programselector H.

At this time the control knob I4 has been rotated from its on positionin the clockwise direction back into its oil? position; operation of theprogram selector II has been arrested; and the cycle of operation of thedishwashing apparatus I 6 has been completed. Thus it will be understoodthat when the manual control knob 14 of the program selector H isrotated from its off position into its on position in the clockwisedirection, further operation ofv the program selector II isautomatically continued under the control of the associated timer motor,whereby the cycle of operation of the dishwashing apparatus I0 iscarried out automatically, a time interval of approximately 2970 secondsbeing required.

During the operation of the dishwashing apparatus I 0 in the timed cycleabove-described, the door I3 must be retained in its closed position inorder to retain the door switch I3 in its closed position, since thedoor switch I3 occupies an interlock position in the control circuitnetwork; and any time the door I3 is operated into its open position,the door switch I3 is operated into its open position arresting thecycle of operation of the dishwashing apparatus Hi. Final- 1y, at theconclusion of the timed washing cycle, the dishes supported by the rackstructure I4 have not only been thoroughly washed and rinsed, but theyhave also been subjected to a drying action. Subsequently, the door I3may be moved from its closed position into its open position, and therack structure [4 may be moved out of the vat over the door I3 so thatthe dishes may be removed from the rack structure I4 and placed in akitchen cabinet, or the like, if desired.

In the operation of the washing apparatus I0, the dishes, glassware,etc., supported by the rack structure [4 are subjected to the initialand the final drying steps, following the secondary rinsing step, underconditions such that there are no droplets of rinsing liquid thereonduring the drying actions. This effect is accomplished by virtue of thepresence of an adequate amount of synthetic wetting agent in the chargeof rinsing liquid during the secondary rinsing step, an excess charge ofsynthettic wetting agent being introduced into the charge of rinsingliquid during the primary rinsing step as a matter of preferredtechnique. Since the dishes, glassware, and the like, undergo the dryingaction without the presence thereon of the water droplets mentioned, itis not critical that the washing and rinsing liquids employed in thedishwashing apparatus It may comprise hard water that'has been merelyheated to the proper temperature in a hot water tank, or the like,without any water softening treatment. Specifically, since the dishes,glassware, etc., are subjected to the drying actions noted in theabsence of the water droplets mentioned, they are not spotted orstreaked at the conclusion of the drying step or subjected to thegradual discoloring efiects that normally proceed from the utilizationof hard water in dishwashing apparatus of this character.

In view of the foregoing, it is apparent that there has been provided animproved .method of washing dishes, or the like, that may be readilycarried out in a known type of automatic dishwashing apparatus, as wellas improved equipment that may be readily installed into the automaticdishwashing apparatus mentioned in order to convert it to carry out thepresent method.

While there has been described what is at present considered to be thepreferred embodi ment of the invention, it will be understood thatvarious modifications may be made therein, and it is intended to coverin the appended claims all such modifications as fall within the truespirit and scope of the invention.

What is claimed is:

1. The method of washing dishes, or the like, arranged in an enclosingvat comprising introducing a first body of hot water into the vat,introducing an excess charge of detergent into the first body of hotwater, circulating the first body of hot water in the vat intobombarding relation with the dishes for a time interval in order toefieet primary washing of substantially all of the soil therefrom,draining the first body of hot water from the vat, introducing a secondbody or" hot water into the vat, circulating the second body of hotwater in the vat into bombarding relation with the dishes for a timeinterval in order to efiect secondary washing of the small residual soiltherefrom, draining the second body of hot water from the vat,introducing a third body of hot water into the vat, introducing anexcess charge of synthetic wetting agent into the third body of hotwater, circulating the third body of hot water in the vat into,

bombarding relation with the dishes for "a" time interval in order toeffect primary rinsing of substantially all of the detergent therefrom,draining the third body of hot water from the vat, introducing a fourthbody of hot water into the vat, circulating the fourth body of hot waterin the vat into bombarding relation with the dishes for a time intervalin order to effect secondary rinsing of the small residual detergenttherefrom, draining the fourth body of hot water from the vat, thelast-mentioned rinse water containing a sufiicient quantity of thesynthetic wetting agent to reduce the surface tension thereof so thatsubstantially all of the last-mentioned rinse water drains freely andquickly from the dishes, and finally retaining the dishes in the vat fora time interval in order to effect evaporation of the small residuum ofthe last-mentioned rinse water thereon and the consequent dryingthereof.

2. The method of washing dishes, or the like, arranged in an enclosingvat comprising introducing a first body of hot water into the vat,introducing an excess charge of detergent into the first body of hotwater, circulatin the first body of hot water in the vat into bombardingrelation with the dishes for a time interval in order to effect primarywashing of substantially all of the soil therefrom, draining the firstbody of hot water from the vat, introducing a second body of hot waterinto the vat, circulating the second body of hot water in the vat intobombarding relation with the dishes for a time interval in order toeffect secondary washing of the small residual soil therefrom, drainingthe second body of hot water from the vat, introducing a third body ofhot water into the vat, introducing an excess charge of syntheticwetting agent into the third body of hot water, circulating the thirdbody of hot water in the vat into bombarding relation with the dishesfor a time interval in order to effect primary rinsing of substantiallyall of the detergent therefrom, draining the third body of hot waterfrom the vat, introducing a fourth body of hot water into the vat,circulating the fourth body of hot water in the vat into bombardingrelation with the dishes for a time interval in order to effectsecondary rinsing of the small residual detergent therefrom, drainingthe fourth body of hot water from the vat, the last-mentioned rinsewater containing a sufficient quantity of the synthetic wetting agent toreduce the surface tension thereof so that substantially all of thelast-mentioned rinse water drains freely and quickly from the dishes,and finally circulating hot air in the vat in the form of a blast intocontact with the dishes for a time interval in order to effectevaporation of the small residuum of the last-mentioned rinse waterthereon and the consequent drying thereof.

3. The method set forth in claim 1, wherein the synthetic wetting agentconsists essentially of an ester of a higher fatty acid, in which thefatty acid portion of the molecule contains from 12 to 18 carbon atoms.

4. The method set forth in claim 1, wherein the synthetic wetting agentconsists essentially of a sulfuric acid ester of a higher fatty acid, inwhich the fatty acid portion of the molecule contains from 12 to 18carbon atoms.

5. The method set forth in claim 1, wherein the synthetic wetting agentconsists essentially of sodium lauryl sulfate.

EDGAR S. STODDARD.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,476,909 Moore Dec. 11, 19 3 1,529,168 Cleveland Mar. 10,1925 1,662,496 Forsgard Mar. 13, 1928 1,847,256 Nielsen Mar. 1, 19322,109,575 Parsons Mar. 1, 1938 2,226,096 Halsey Dec. 24, 1940 2,385,264Ferris Sept. 18, 1945 2,390,757 Voris Dec. 11, 1945 2,509,003 LathropMay 23, 1950

1. THE METHOD OF WASHING DISHES, OR THE LIKE, ARRANGED IN AN ENCLOSINGVAT COMPRISING INTRODUCING A FIRST BODY OF HOT WATER INTO THE VAT,INTRODUCING AN EXCESS CHARGE OF DETERGENT INTO THE FIRST BODY OF HOTWATER, CIRCULATING THE FIRST BODY OF HOT WATER IN THE VAT INTOBOMBARDING RELATION WITH THE DISHES FOR A TIME INTERVAL IN ORDER TOEFFECT PRIMARY WASHING OF SUBSTANTIALLY ALL OF THE SOIL THEREFROM,DRAINING THE FIRST BODY OF HOT WATER FROM THE VAT, INTRODUCING A SECONDBODY OF HOT WATER INTO THE VAT, CIRCULATING THE SECOND BODY OF HOT WATERIN THE VAT INTO BOMBARDING RELATION WITH THE DISHES FOR A TIME INTERVALIN ORDER TO EFFECT SECONDARY WASHING OF THE SMALL RESIDUAL SOILTHEREFROM, DRAINING THE SECOND BODY OF HOT WATER IN THE VAT, INTRODUCINGA THIRD BODY OF HOT WATER INTO THE VAT, INTRODUCING AN EXCESS CHARGE OFSYNTHETIC WETTING AGENT INTO THE THIRD BODY OF HOT WATER, CIRCULATINGTHE THRID BODY OF HOT WATER IN THE VAT INTO BOMBARDING RELATION WITH THEDISHES FOR A TIME INTERVAL IN ORDER TO EFFECT PRIMARY RINSING OFSUBSTANTIALLY ALL OF THE DETERGENT THEREFROM, DRAINING THE THIRD BODY OFHOT WATER FROM THE VAT, INTRODUCING A FOUTH BODY OF HOT WATER INTO THEVAT, CIRCULATING THE FOURTH BODY OF HOT WATER IN THE VAT INTO BOMBARDINGRELATION WITH THE DISHES FOR A TIME INTERVAL IN ORDER TO EFFECTSECONDARY RINSING OF THE SMALL RESIDUAL DETERGENT THEREFROM, DRAININGTHE FOURTH BODY OF HOT WATER FROM THE VAT, THE LAST-MENTIONED RINSEWATER CONTAINING A SUFFICIENT QUANTITY OF THE SYNTHETIC WETTING AGENT TOREDUCE THE SURFACE TENSION THEREOF SO THAT SUBSTANTIALLY ALL OF THELAST-MENTIONED RINSE WATER DRAINS FREELY AND QUICKLY FROM THE DISHES,AND FINALLY RETAINING THE DISHES IN THE VAT FOR A TIME INTERVAL IN ORDERTO EFFECT EVAPORATION OF THE SMALL RESIDUUM OF THE LAST-MENTIONED RINSEWATER THEREON AND THE CONSEQUENT DRYING THEREOF.